U.S. patent number 9,285,354 [Application Number 13/607,921] was granted by the patent office on 2016-03-15 for systems and methods for the detection of low-level harmful substances in a large volume of fluid.
This patent grant is currently assigned to The United States of America as represented by the Administrator of the U.S. Environmental Protection Agency. The grantee listed for this patent is Michael V. Carpenter, Vincente Gallardo, Alan Lindquist, Lyle G. Roybal. Invention is credited to Michael V. Carpenter, Vincente Gallardo, Alan Lindquist, Lyle G. Roybal.
United States Patent |
9,285,354 |
Carpenter , et al. |
March 15, 2016 |
Systems and methods for the detection of low-level harmful
substances in a large volume of fluid
Abstract
A method and device for the detection of low-level harmful
substances in a large volume of fluid comprising using a
concentrator system to produce a retentate and analyzing the
retentate for the presence of at least one harmful substance. The
concentrator system performs a method comprising pumping at least
10 liters of fluid from a sample source through a filter. While
pumping, the concentrator system diverts retentate from the filter
into a container. The concentrator system also recirculates at
least part of the retentate in the container again through the
filter. The concentrator system controls the speed of the pump with
a control system thereby maintaining a fluid pressure less than 25
psi during the pumping of the fluid; monitors the quantity of
retentate within the container with a control system, and maintains
a reduced volume level of retentate and a target volume of
retentate.
Inventors: |
Carpenter; Michael V. (Idaho
Falls, ID), Roybal; Lyle G. (Idaho Falls, ID), Lindquist;
Alan (Cincinnati, OH), Gallardo; Vincente (Cincinnati,
OH) |
Applicant: |
Name |
City |
State |
Country |
Type |
Carpenter; Michael V.
Roybal; Lyle G.
Lindquist; Alan
Gallardo; Vincente |
Idaho Falls
Idaho Falls
Cincinnati
Cincinnati |
ID
ID
OH
OH |
US
US
US
US |
|
|
Assignee: |
The United States of America as
represented by the Administrator of the U.S. Environmental
Protection Agency (Washington, DC)
|
Family
ID: |
49156419 |
Appl.
No.: |
13/607,921 |
Filed: |
September 10, 2012 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130239666 A1 |
Sep 19, 2013 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
11695432 |
Apr 2, 2007 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D
63/02 (20130101); G01N 1/4005 (20130101); B01D
61/147 (20130101); G01N 15/0618 (20130101); G01N
33/1866 (20130101); G01N 1/14 (20130101); G01N
2015/0065 (20130101); G01N 2001/4088 (20130101); G01N
2015/0046 (20130101) |
Current International
Class: |
G01N
1/40 (20060101); G01N 15/06 (20060101); G01N
33/18 (20060101); G01N 1/14 (20060101); B01D
63/02 (20060101); B01D 61/14 (20060101); G01N
1/10 (20060101); B01D 61/22 (20060101); B01D
61/10 (20060101); C02F 1/44 (20060101); G01N
15/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Lindquist et al. Using ultrafiltration to concentrate and detect
Bacillus anthracis, Bacillus atrophaeus subspecies globigii, and
Cryptosporidium parvum in 100-liter water samples. Journal of
Microbiological Methods 70 (2007) 484-492. cited by examiner .
Hill et al. Development of a rapid method for simultaneous recovery
of diverse microbes in drinking water by ultrafiltration with
sodium polyphosphate and surfactants. Applied and Environmental
Microbiology (Nov. 2005) 6878-6884. cited by examiner.
|
Primary Examiner: Zalasky; Katherine
Attorney, Agent or Firm: Weiss & Moy, PC
Government Interests
GOVERNMENT RIGHTS
The United States Government has certain rights in this invention
pursuant to Contract No. DE-AC07-05ID14517 between the United
States Department of Energy and Battelle Energy Alliance, LLC.
Parent Case Text
RELATED APPLICATIONS
This U.S. non-provisional application is a continuation-in-part
application of and claims priority to U.S. non-provisional
application Ser. No. 11/695,432 filed Apr. 2, 2007, which is hereby
fully incorporated by reference in its entirety.
Claims
What is claimed is:
1. A method for the detection of low-level harmful substances in a
volume of fluid comprising: a) using a concentrator system to
perform a method comprising: i) pumping at least 10 liters of fluid
from a sample source through a filter and back into said sample
source; said filter preventing the passage of at least one harmful
substance; ii) diverting retentate from said filter into a
container that is separate from said sample source; iii)
recirculating at least part of said retentate in said container
again through said filter; iv) circulating air to and from said
container through an air filter; v) preventing the release of said
retentate out of said concentrator system; vi) controlling the
speed of a pump with a control system thereby maintaining a fluid
pressure less than 25 PSI during said pumping of said fluid; vii)
monitoring the quantity of retentate within said container with a
control system and maintaining the quantity of retentate within a
predetermined range comprising: (1) detecting a value of the volume
or weight of said retentate; (2) controlling the amount of
retentate diverted in said step of diverting retentate; and (3)
selectively drawing in additional fluid from said sample source in
order to maintain said quantity of retentate within said container
within said predetermined range; and b) analyzing said retentate
for the presence of at least one harmful substance.
2. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 further comprising monitoring for
leaks within said concentrator system.
3. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1: a) further comprising transporting
said container to a location different from said sample source; and
b) whereby said step of analyzing said retentate comprises
analyzing said retentate at said different location.
4. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of analyzing said
retentate comprises analyzing said retentate with one or more
analyzers within said concentrator system notifying a user of the
results.
5. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said filter comprises a
blocking solution.
6. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said filter comprises a
blocking solution consisting essentially of water, polysorbate 80,
an antifoaming agent, and sodium polyphosphate.
7. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 further comprising after said step of
pumping at least 10 liters of fluid from said sample source through
said filter pumping an elution solution.
8. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 further comprising after said step of
pumping at least 10 liters of fluid from said sample source through
said filter pumping an elution solution consisting essentially of
water and 0.001% polysorbate 80.
9. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of pumping at least
10 liters of fluid from said sample source through said filter
comprises pumping fluid from said sample source using a single
pump.
10. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of pumping at least
10 liters of fluid from said sample source through said filter
comprising pumping at least 100 liters of fluid.
11. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of pumping at least
10 liters of fluid from said sample source through said filter
comprising pumping 100 liters of fluid.
12. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of pumping at least
10 liters of fluid from said sample source through said filter
comprising pumping less than 2.9 liters per minute of fluid.
13. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of controlling the
amount of retentate diverted further comprises diverting less than
500 ml of retentate per 100 liters of fluid from said sample source
into said retentate container.
14. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of controlling the
amount of retentate diverted further comprises diverting less than
250 ml of retentate per 100 liters of fluid from said sample source
into said retentate container.
15. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of analyzing said
retentate comprises: a) detecting an amount of one or more harmful
substances in said retentate; b) determining a concentration factor
of said retentate from the ratio of a volume of said fluid that was
pumped from said sample source to a volume of said monitored
quantity of retentate; and c) multiplying the amount of each
harmful substance that has been detected in said retentate by said
determined concentration factor thereby producing the amount of
each harmful substance in said at least 10 liters of fluid that was
pumped from said sample source.
16. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step diverting retentate
from said filter into a container comprises directing said
retentate along the inner walls of said container.
17. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby: a) said step of detecting a
value of the volume or weight of said retentate comprises a
measuring device connected to said container; and b) said step of
diverting retentate from said filter comprises diverting retentate
from said filter into said container in a manner that is
perpendicular to said measuring device.
18. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of circulating air
to and from said container through an air filter comprises
circulating air to and from said container through a
High-efficiency Particulate Arrestance (HEPA) filter.
19. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said filter comprises a
plurality of hollow fibers extending through the body of said
filter.
20. The method for the detection of low-level harmful substances in
a volume of fluid of claim 19 whereby each of said hollow fibers of
said filter comprises a longitudinally extending central lumen
surrounded by a porous wall, said porous wall comprising a
plurality of pores having an average pore size selected to prevent
said at least one harmful substances from passing through said
plurality of pores.
21. The method for the detection of low-level harmful substances in
a volume of fluid of claim 20 whereby said porous walls of said
hollow fibers of said filter have an average pore size of between
about fifty nanometers (50 nm) and about two microns (2 .mu.m).
22. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said predetermined range is
between a reduced volume level of retentate of 250 ml and a target
volume of retentate of 750 ml.
23. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 whereby said step of pumping at least
10 liters of fluid from said sample source through said filter and
back into said sample source comprises pumping fluid through at
least one loop of conduit and then through said filter.
24. The method for the detection of low-level harmful substances in
a volume of fluid of claim 1 further comprising: a) monitoring for
leaks within said concentrator system; b) after said step of
pumping at least 10 liters of fluid from said sample source through
said filter pumping an elution solution; and whereby c) said filter
comprises a blocking solution; d) said step of pumping at least 10
liters of fluid from said sample source through said filter
comprising pumping at least 100 liters of fluid; e) said step of
controlling the amount of retentate diverted further comprises
diverting less than 500 ml of retentate per 100 liters of fluid
from said sample source into said retentate container; f) said step
of diverting retentate from said filter into said container
comprises directing said retentate along the inner walls of said
container; and g) said step of circulating air to and from said
container through an air filter comprises venting air to and from
said container through a High-efficiency Particulate Arrestance
(HEPA) filter.
25. The method for the detection of low-level harmful substances in
a volume of fluid of claim 24 further comprising: a) said step of
pumping at least 10 liters of fluid from said sample source through
said filter comprises pumping fluid from said sample source using a
single pump; b) said step of pumping at least 10 liters of fluid
from said sample source through said filter comprising pumping less
than 2.9 liters per minute of fluid; c) said step of controlling
the amount of retentate diverted further comprises diverting less
than 250 ml of retentate per 100 liters of fluid from said sample
source into said retentate container; d) said step of analyzing
said retentate comprises: i) detecting an amount of one or more
harmful substances in said retentate; ii) determining a
concentration factor of said retentate from the ratio of a volume
of said fluid that was pumped from said sample source to a volume
of said monitored quantity of retentate; and iii) multiplying the
amount of each harmful substance that has been detected in said
retentate by said determined concentration factor thereby producing
the amount of each harmful substance in said at least 10 liters of
fluid that was pumped from said sample source; e) said step of
detecting a value at least relating to the volume or weight of said
retentate comprises a measuring device connected to said container;
said step of diverting retentate from said filter comprises
diverting retentate from said filter into said container in a
manner that is perpendicular to said measuring device; and g) said
step of pumping at least 10 liters of fluid from said sample source
through said filter and back into said sample source comprises
pumping fluid through at least one loop of conduit and then through
a filter.
26. The method for the detection of low-level harmful substances in
a volume of fluid of claim 25 whereby: a) said elution solution
consisting essentially of water and polysorbate 80; b) said filter
comprises said blocking solution that is consisting essentially of
water, polysorbate 80, an antifoaming agent, and sodium
polyphosphate; c) said step of pumping at least 10 liters of fluid
from said sample source through said filter comprising pumping 100
liters of fluid; d) said reduced volume level of retentate is 250
ml; e) said target volume of retentate is 750 ml; f) said filter
comprises a longitudinally extending central lumen surrounded by a
porous wall, said porous wall comprising a plurality of pores
having an average pore size selected to prevent said at least one
harmful substances from passing through said plurality of pores;
and g) said porous walls of said hollow fibers of said plurality of
hollow fibers have an average pore size of between about fifty
nanometers (50 nm) and about two microns (2 .mu.m).
27. The method for the detection of low-level harmful substances in
a volume of fluid of claim 26 further comprising: a) transporting
said container to a location different from said sample source; and
whereby b) said step of analyzing said retentate comprises
analyzing said retentate at said different location.
28. The method for the detection of low-level harmful substances in
a volume of fluid of claim 26 further comprising said step of
analyzing said retentate comprises analyzing said retentate with
one or more analyzers within said concentrator system notifying a
user of the results.
Description
FIELD OF THE INVENTION
Embodiments of the present invention relate to systems and methods
for the detection of low-level harmful substances, preferably
pathogens, in a fluid sample. Preferably, the systems and method
described herein are used to detect low-level harmful substances in
a large volume of fluid that would otherwise be undetectable
without transporting the large volume of fluid to a testing site
for concentration and analysis.
BACKGROUND OF THE INVENTION
There are many applications in which it is desired to detect the
presence and, preferably the concentration of harmful substances
even low-level, in a fluid. By way of example and not limitation,
it may be desired to detect the presence and concentration of a
microbial pathogen in a source of drinking water such as, for
example, a lake, reservoir, river, stream, storage tank, water
main, or well. Some harmful substances may be difficult to detect
using conventional methods at lower concentrations. For instance,
certain microbial pathogens may be harmful to human health at
concentrations that are too low to accurately, reliably, and
economically detect using conventional methods. Furthermore, in
some situations, the sample size used in conventional detection
methods may not provide testing results that reflect the actual
concentration in the source from which the sample was obtained with
an acceptable level of accuracy or certainty. For example, the
concentration of a microbial pathogen in a few milliliters of water
taken from a source of drinking water may not accurately represent
the actual average concentration of the microbial pathogen in that
source. As a result, analysis of multiple samples from a single
fluid source may be required to determine the concentration of a
harmful substance in the fluid source with an acceptable level of
certainty.
For each of the above reasons, it has been proposed in the art to
concentrate a fluid sample taken from a fluid source by a known
concentration factor prior to determining the concentration of a
harmful substance in the concentrated fluid sample. Once the
concentration of the harmful substance in the concentrated fluid
sample has been determined, the concentration in the unconcentrated
fluid sample can be determined using the known concentration factor
by which the fluid sample was concentrated.
As one example, it may be desired to know the concentration of a
particular microbial pathogen in a source. A relatively large
sample of water (e.g., about 100 liters) may be taken from the
source. Some of the water may be separated or removed from the
relatively large sample of water without separating or removing any
significant number of the microbial pathogens of interest to
provide a relatively smaller concentrated sample (e.g., about 1
liter) that includes substantially all of the microbial pathogens
in the original relatively large sample of water. The identity and
concentration of the microbial pathogens in the relatively smaller
concentrated sample then may be determined, and the known identity
and concentration of these pathogens in the concentrated sample may
be used to determine the concentration in the original
unconcentrated sample of water and, hence, the approximate
concentration in the source.
Such methods may result in relatively higher concentrations of the
harmful substance in the concentrated sample that are more readily
detectible using conventional analytical techniques than if these
analytical techniques were used to attempt to detect these harmful
substances at the concentrations in the unconcentrated sample, and
may result in measurements that more accurately reflect the actual
presence and concentration of the harmful substance in the fluid
source from which the sample was obtained for analysis.
There remains a need in the art for systems and methods that are
portable, automated, that provide accurate and repeatable
measurements, that provide acceptable concentration factors in
acceptable amounts of time, and that minimize or reduce the risk of
exposure of an operator to any harmful substance potentially
carried by the fluid sample.
BRIEF SUMMARY OF THE INVENTION
A method and device for the detection of low-level harmful
substances in a large volume of fluid comprising using a
concentrator system to produce a retentate and analyzing the
retantate for the presence of at one harmful substance. The
concentrator system performs a method comprising pumping at least
10 liters of fluid from a sample source through a filter, where a
percentage of the fluid crosses the filter wall and is discharged
and the remaining percentage of water is recycled back to the
filter inlet. The filter prevents the passage of at least one
harmful substance. While pumping, the concentrator system diverts
retentate from the filter into a container. While pumping, the
concentrator system recirculates at least part of the retentate in
the container again through the filter. The concentrator system
also vents air to and from the container through an air filter,
thereby preventing the release of at least one harmful substance
out of the concentrator system. The concentrator system also
controls the speed of the pump with a control system thereby
maintaining a fluid pressure less than 25 psi during the pumping of
the fluid; monitors the quantity of retentate within the container
with a control system, and maintains a reduced volume level of
retentate and a target volume of retentate. The concentrator system
preferably maintains the volume of retentate in the container so
that it is within an operator defined range and so that the final
volume of retentate meets an operator specified value. The method
of maintaining a reduced volume level of retentate and a target
volume of retentate comprises detecting a value at least relating
to the volume or weight of the retentate; and controlling the
amount of retenate diverted in the step of diverting retentate.
Preferably, the concentrator system is monitored for leaks,
preferably through the use of a water sensor. Preferably, the
container containing the final volume of retentate is transported
to a location different from the sample source, where it is
subsequently analyzed for one or more harmful substances.
Preferably, a blocking solution is added to the filter. A blocking
solution is a solution for preventing one or more harmful
substances from bonding with the filter, preferably polysorbate 80
and sodium polyphosphate. Polysorbate 80 is preferred as it makes
the surface of the filter more hydrophilic. Sodium polyphosphate is
preferred as it makes the surface of the filter electronegative.
More preferably, the blocking solution further comprises one or
more compounds designed to prevent foaming, preferably a silicone
polymer-based antifoaming agent sold under the name ANTIFOAM A. In
a preferred embodiment, the blocking solution consists essentially
of water, polysorbate 80, ANTIFOAM A and sodium polyphosphate.
Preferably, an elution solution is passed through the system after
the large volume sample has been drawn into the system. The elution
solution preferably comprises anything that will help loosen one or
more harmful substances, more preferably polysorbate 80.
Preferably, the pumping is performed by a single pump. Preferably,
the pumping pumps at least 100 liters, more preferably 100 liters.
Preferably, the pumping is less than 2.9 liters per minute of
fluid. Preferably the amount of retentate retained after being
diverted produces less than 500 ml of retentate per 100 liters of
fluid. Preferably the amount of retentate retained after being
diverted produces less than 250 ml of retentate per 100 liters of
fluid.
Preferably, the retentate is analyzed detecting the amount of one
or more harmful substances. The concentration factor of the
retentate is then preferably determined from the ratio of the
pumped fluid to the electrically monitored quantity of retentate.
Each detected one or more harmful substances in the transported
retentate is then preferably multiplied by the determined
concentration factor thereby producing the number of harmful
substances in the pumped fluid.
Preferably, retentate is diverted from the filter into the
container by directing the retentate along the inner walls of the
container, which is preferred as it will minimize the generation of
foam. Foam is preferably minimized as it will impeded analyzing of
the resulting retentate and also poses as a threat to safety. In a
preferred embodiment, a measuring device is connected to the
container and the retentate is diverted perpendicular to the
measuring device. This embodiment is advantageous as it will
prevent the influx of retentate from affecting measurements, while
also minimizing foam generation. Preferably, the fluid is pumped
through at least one loop of conduit before it us pumped through
the filter, thereby reducing vibrations which may damage the filter
over time.
In some embodiments, the present invention includes methods of
concentrating one or more harmful substances in a fluid. The
methods include establishing circulation of fluid flow through a
filter, causing fluid to exit the fluid circulation path through a
filtering element of the filter, and preventing the one or more
harmful substances from passing through the filtering element. The
fluid circulation path may also pass through a retentate container
and a pump, which may be used to drive fluid flow through the fluid
circulation path. A control system may be used to control one or
more components of the concentrator system. In some embodiments,
the control system may be used to control a speed of the pump. In
other embodiments, the control system may be used to control a
quantity of retentate within the retentate container. In yet
additional embodiments, the control system may be used to control
both a speed of operation of the pump and a quantity of retentate
within the retentate container.
In additional embodiments, the present invention includes systems
for concentrating one or more harmful substances in a fluid. The
systems include a circulating fluid pathway passing through a pump,
a filter, and a retentate container. An effluent outlet line
communicates with the circulating fluid pathway through a filtering
element of the filter. A control system may be used to
automatically control operation of one or more elements or
components of the system (e.g., the pump) in response to a signal
received from a sensor. For example, in some embodiments, the
control system may include more than one sensor. For example, the
control system may include one or more of a retentate sensor
configured to sense a quantity of retentate within the retentate
container, an effluent sensor configured to sense a quantity of
effluent passing through the effluent outlet line, and a pressure
sensor configured to sense a pressure at a location within the
circulating fluid pathway. In some embodiments, the filter,
retentate container, and the pump may be disposed within a housing
or container for portability.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
While the specification concludes with claims particularly pointing
out and distinctly claiming that which is regarded as the present
invention, the advantages of this invention may be more readily
ascertained from the following description of the invention when
read in conjunction with the accompanying drawings in which:
FIG. 1 is a simplified process flow diagram illustrating
operational principles of embodiments of sample concentrator
systems of the present invention;
FIG. 2 is a process and instrumentation diagram schematically
illustrating an embodiment of a sample concentrator system of the
present invention;
FIG. 3 is a Nock diagram schematically illustrating an embodiment
of a control system that may be used to control operation of the
sample concentrator system shown in FIG. 2;
FIGS. 4A-4C illustrate a flow chart showing a sequence of
operations that may be performed by the control system shown in
FIG. 3;
FIG. 5 is a partially cut-away perspective view illustrating one
particular embodiment of a portable sample concentrator system of
the present invention; and
FIG. 6 is a schematic top plan view of the portable sample
concentrator system shown in FIG. 5 and illustrates one example of
a manner in which the various elements, components, and subsystems
of the portable sample concentrator system may be located and
secured within an outer housing of the portable sample concentrator
system.
DETAILED DESCRIPTION OF THE INVENTION
Several of the illustrations presented herein are not meant to be
actual views of any particular sample concentrator system or
apparatus, but are merely idealized representations which are
employed to describe the present invention. Additionally, elements
common between figures may retain the same numerical
designation.
A harmful substance is any substance harmful to any living
organism, preferably humans, and without limitation whether such
substance may be characterized as a pathogen, contaminant, a toxic
substance, a substance artificially introduced into the fluid, or a
naturally occurring substance. Preferably, the harmful substance is
a pathogen. More preferably, the harmful substance is the causative
agent for diseases such as tularemia, anthrax, smallpox, bubonic
plague, viral hemorrhagic fevers, brucellosis, glanders,
melioidosis, psittacosis, Q fever, salmonella, shigellosis, Typhus,
staphylococcal infections, Viral encephalitis, cholera,
cryptosporidiosis, E. coli O157:H7 infection, viral infections due
to Nipah virus, Hantavirus, or H1N1, or a toxin such as Botulinum,
Epsilon toxin of Clostridium perfringens, ricin, abrin,
staphylococcal enterotoxin B, or a combination thereof. In
preferred embodiments the harmful substances include the causative
agents of tularemia, anthrax, smallpox, botulism, bubonic plague,
viral hemorhaigic fevers due to the contagiousness and
high-mortality rate of these agents. In another preferred
embodiment, the harmful substances include the causative agents of
cholera and cryptosporidiosis due to the significant water supply
threat of these agents.
A low-level harmful substance is a harmful substance not normally
detectable without concentrating the harmful substance. More
preferably, a low-level harmful substance is a substance having a
level less than 1 microorganism per 1 liter.
FIG. 1 is a simplified process flow diagram illustrating principles
that may be used to concentrate a harmful substance in a fluid
sample according to embodiments of methods of the present
invention. Such methods also may be carried out using embodiments
of sample concentrator systems of the present invention. As shown
in FIG. 1, a circular fluid path may be established using conduits
such as pipes or hoses (not shown in FIG. 1) that passes through a
pump, a filter, and a retentate container. As used herein, the
terms "circular" and "circulating" mean and include a substantially
continuous fluid path, without the exclusion of inlets thereto and
outlets therefrom, and are not restricted to any particular
physical path shape. The pump may be used to drive recirculating
fluid flow within the circular fluid path. The fluid path may be
primed with a fluid from a sample source that is potentially
contaminated with a harmful substance, as also shown in FIG. 1. The
sample source may comprise, for example, water from a lake,
reservoir, river, stream, storage tank, water main or well. The
filter may be configured to allow fluid to exit the circular fluid
path as effluent, while preventing at least one harmful substance
from exiting the circular fluid path. As fluid is removed from the
circular fluid path through the filter, additional fluid may be
drawn from the sample source as necessary to maintain a
predetermined volume of fluid in the circular fluid path and within
the retentate container. As the potentially contaminated fluid
recirculates within the fluid circulation path, the concentration
of one or more harmful substances may increase within the circular
fluid path and the retentate container as additional pathogens and
other harmful matter enters the circulating fluid path from the
sample source but is prevented from leaving the circulating fluid
path through the filter. After a predetermined or selected
concentration factor has been achieved (i.e., a predetermined or
selected volume of potentially contaminated fluid has been drawn
into the fluid-circulation path and processed by the filter), a
volume of the potentially contaminated concentrated fluid may be
removed from the retentate container for testing and analysis. For
example, the volume of the potentially contaminated fluid may be
tested to detect the presence of one or more harmful substances,
such as pathogens (e.g., microbial pathogens), for example, within
the fluid taken from the sample source, and optionally, to estimate
or determine the concentration of one or more harmful substances
within the fluid taken from the sample source.
FIG. 2 is a process and instrumentation diagram schematically
illustrating an embodiment of a sample concentrator system 10 of
the present invention. As shown in FIG. 2, the concentrator system
10 includes a pump 12, a filter 14, and a retentate container 16.
As discussed in further detail below, the concentrator system 10
also includes a plurality of conduits defining a circulating fluid
path passing through the pump 12, the filter 14, and the retentate
container 16, as well as one or more conduits defining a sample
source inlet line for drawing potentially contaminated fluid into
the circulating fluid path, and one or more conduits defining an
effluent outlet line for allowing fluid to exit the circulating
fluid path.
The pump 12 is used to drive fluid flow of the potentially
contaminated fluid through the concentrator system 10. In some
embodiments, the pump 12 may comprise a peristaltic pump, in which
one or more "rollers," "shoes," or "wipers" are caused to compress
and wipe along the exterior surface of a flexible closed tube
passing through the pump, which causes fluid to flow within the
tube in the direction in which the wipers wipe along the tube.
Using a peristaltic pump may prevent direct physical contact
between the potentially contaminated fluid and any part of the
pump, which may reduce the potential for contamination and
corrosion, and prevents the accumulation of any harmful substance
on parts or components of the pump, the presence of which harmful
substance or substances could alter the detected concentration
levels of the harmful substance within the circulating fluid path.
Such peristaltic pumps are commercially available. As one
particular non-limiting example, the pump 12 may comprise a
MASTERFLEX.RTM. I/P.RTM. Precision Brushless Drive Model No.
77410-10, available from Cole-Parmer Instrument Co. of Vernon
Hills, Ill., fitted with a MASTERFLEX.RTM. I/P.RTM. EASY-LOAD.RTM.
Pump Head Model No. 77601-00, which is also available from
Cole-Parmer Instrument Co. In additional embodiments, the
concentrator system 10 may comprise any other type of pump capable
of driving fluid flow through the concentrator system 10.
The pump 12 is preferably positioned to prevent any leak from the
conduit from reaching any electronic components 118 the pump 12, or
other electronics in the system. Although the pump 12 is shown in
FIG. 5 facing the viewer for simplicity, the pump 12 is preferably
positioned whereby the conduit is within in the same compartment
(e.g. the right-hand side of FIG. 5). This embodiment is preferred
to ensure that any leaks from the conduit are within a compartment
designated for leaks and away from electronics that may be easily
damaged.
With continued reference to FIG. 2, fluid may flow from the pump 12
to the filter 14 through a conduit 18. Although not shown for
simplicity, the conduit 18 preferably has at least one loop to
reduce vibrations which may damage the filter over time.
The filter 14 is used to allow fluid to exit the circulating fluid
path of the concentrator system 10, while preventing one or more
harmful substances, such as, for example, pathogens, from exiting
the circulating fluid path of the concentrator system 10. In some
embodiments, the filter 14 may comprise a plurality of
longitudinally oriented hollow fibers disposed within a filter
body, such as those filters disclosed in U.S. Pat. No. 5,531,848 to
Brinda et al., the disclosure of which is incorporated herein in
its entirety by this reference. By way of example and not
limitation, each of the hollow fibers may have an average diameter
of between about 100 microns and about 1,000 microns, and may be
formed from a material having pores or apertures having an average
pore size of between about fifty nanometers (50 nm) and about to
microns (2.mu.). Such filters may have a molecular cutoff in the
range from about 500 Da to about 500 kDa. More particularly in
certain embodiments an ultrafiltration filter may have a molecular
cutoff in the range from about 15 kDa to about 75 kDa. In other
embodiments nanofilters with a molecular cutoff of less than about
500 Da may be used or microfilters with a molecular cutoff of
greater than about 500 kDa may be used. The so-called filtrate or
retentate moves longitudinally through the hollow fibers and
through the filter body without passing through the pores in the
walls of the fibers, while water and other low molecular weight
components (often referred to as "permeate") pass through the pores
in the walls of the fibers in a direction generally transverse to
the general flow of the retentate through the fibers. In other
words, the walls of the hollow fibers form or comprise the
filtering element of the filter 14. Some fluid passes transversely
through the walls of the hollow fibers, while other fluid and the
harmful matter being concentrated passes longitudinally through the
hollow fibers and the filter body, but not through the walls of the
hollow fibers (the filtering element). As non-limiting examples,
the filter 14 may comprise a HEMOCOR HPH.RTM. filter, Model No. HPH
1400 as sold by Minntech, APS series Dialyzer as sold by Asahi
Kasei, EXELTRA PLUS 201 as sold by Baxter Corp, F200NR as sold by
Fresenuis Miedical Co, and REXEED as sold by Asahi Kasei.
As shown in FIG. 2, an effluent outlet line 20, which communicates
with the circulating fluid path through the filtering element of
the filter 14, may extend from the filter 14 to a connector or
fitting, to an effluent container, or to another suitable
repository for the effluent. In situations in which the sample
source is relatively large, such as, for example, drinking water
storage tank, a drinking water distribution system, a lake,
reservoir, river, a stream, a water main or stream, the effluent
outlet line 20 may extend back to the sample source at a location
sufficiently remote from the location at which potentially
contaminated fluid is being drawn into the concentrator system 10
so as to not affect the concentration of harmful substances in the
fluid being drawn into the concentrator system 10.
One or more conduits 22 may be used to allow retentate (fluid and
harmful matter that has not passed through the filtering element of
the filter 14) to flow from the filter 14 to the retentate
container 16.
The retentate container 16 is used to accumulate a desired volume
of potentially contaminated fluid or retentate in the concentrator
system 10 for subsequent testing and analysis. In some embodiments,
the retentate container may be easily removable from the
concentrator system 10 to allow an operator to remove the retentate
container 16 from the concentrator system 10 to facilitate
transportation or shipment of the retentate container 16 and the
potentially contaminated retentate therein to a laboratory or other
location for testing and analysis. Furthermore, the retentate
container 16 may be configured to minimize exposure of an operator
of the concentrator system 10 to any pathogens or other harmful
substances that may be present within the retentate container 16
when the operator removes the retentate container 16 from the
concentrator system 10 or otherwise handles the retentate container
16.
By way of example and not limitation, the retentate container 16
may comprise a glass or plastic carboy or bottle. In some
embodiments, the retentate container 16 may comprise a material
that is autoclavable such as, for example, glass or polypropylene.
As one particular nonlimiting example, the retentate container 16
may comprise a NALGENE.RTM. autoclavable polypropylene one liter (1
L) bottle. Such bottles are commercially available from, for
example, Thermo Fisher Scientific Inc. of Waltham, Mass.
With continued reference to FIG. 2, one or more conduits 24 may be
used to allow retentate to flow from the retentate container 16
back to the pump 12. As shown in FIG. 2, in some embodiments, one
end of a conduit 24 may be positioned in the lower interior region
of the container 16 to allow fluid within the retentate container
16 to be drawn into the conduit 24 by the pump 12 even when the
fluid level within the retentate container is low. A vent line 26
may also be used to provide communication between the upper
interior region of the container 16 and the exterior of the
container 16 to allow venting of the retentate container 16 as
necessary or desired. In some embodiments, the container 16 may be
fitted with a so-called "filling/venting cap," which may be used to
couple the conduit 22, the conduit 24, and the vent line 26 to the
retentate container 16. Such filling/venting closures also are
commercially available from, for example, Thermo Fisher Scientific
Inc. of Waltham, Mass.
As shown in FIG. 2, in some embodiments, a coupler 28 may be
provided in one or more of the conduits 22, 24, and 26 at a
location proximate the retentate container 16 to allow the
retentate container 16 to be quickly and easily disconnected from
the concentrator system 10. By way of example and not limitation,
each coupler 28 may comprise a so-called male-to-female Luer Lock
type connector or other suitable connectors such as for example,
straight connectors, hose connectors, barb connectors, ISO
connectors, sanitary connectors, or quick disconnect connectors.
Optionally, one or more of the couplers 28 may comprise a
stopcock.
As shown in FIG. 2, a three-way connector 30 may be used to couple
a sample inlet line 32 to the conduits 24 extending between the
retentate container 16 and the pump 12. The sample inlet line 32
may be used to draw potentially contaminated fluid into the
concentrator system 10 by the pump 12 from a sample source.
The fluid concentrator system 10 may comprise one or more valves
that can be used to selectively control fluid flow through the
system 10. For example, a valve 34A may be provided along the
conduit 22 extending between the filter 14 and the retentate
container 16, a valve 34B may be provided along the conduit 24
extending between the retentate container 16 and the pump 12, and a
valve 34C may be provided along the vent line 26. The fluid
concentrator system 10 also may comprise a valve 34D along the
effluent outlet line 20 and a valve 34E along the sample inlet line
32, as also shown in FIG. 2. A check valve 36 also may be provided
along the sample inlet line 32 that allow fluid flow in only one
direction therethrough (i.e., in the direction extending from the
fluid sample source to the pump 12) to prevent back flow of fluid
out from the fluid circulation path of the concentration system 10
through the sample inlet line 32.
The valves 34A-34E may comprise on-off shutoff type valves, or they
may comprise variable flow control valves. By way of example and
not limitation, the valves 34A-34E may comprise pinch valves that
are configured to pinch flexible tubing of the conduit extending
there through. In some embodiments, such pinch valves may be
configured to pinch the flexible tubing of the conduit using an
electrically operated solenoid or a pneumatically or hydraulically
operated drive element, and may be automatically actuated by a
signal received from a controller, as discussed in further detail
below. In other embodiments, one or more of the valves 34A-34E may
be manually operated and may comprise, for example, a simple
manually actuated tubing clamp.
In some embodiments, each of the conduits 18, 22, 24, as well as
the effluent outlet line 20, the vent line 26, and the sample inlet
line 32 may comprise hollow flexible polymeric tubing.
In some embodiments, one or more features or functions of the
sample concentrator system 10 may be substantially automatically
operated or controlled using a controller, and the concentrator
system 10 may include one or more sensors, meters, or gauges for
monitoring one or more conditions of the concentrator system 10 and
relaying signals indicative of such conditions to the controller to
enable the controller to automatically adjust one or more operating
parameters of the system 10 in response to the signals as necessary
or desired.
By way of example and not limitation, the sample concentrator
system 10 may include one or more pressure gauges for measuring the
fluid pressure at selected locations within the system 10. As shown
in FIG. 2, the concentrator system 10 may include a pressure gauge
42 for measuring the pressure of the fluid within the conduit 18
extending between the pump 12 and the filter 14. The pressure gauge
42 may be configured to generate a signal indicative of the
pressure and to relay the signal to a controller, described in
further detail below. The sample concentrator system 10 also may
include one or more flow sensors for measuring the rate of fluid
flow at selected locations within the system 10.
As shown in FIG. 2, the concentrator system 10 may include a flow
sensor 44 for measuring the flow rate of fluid exiting the
concentrator system 10 through the effluent outlet line 20. The
flow sensor 44 may be configured to generate a signal indicative of
the flow rate and to relay the signal to the controller.
The sample concentrator system 10 also may include one or more
sensors for measuring the volume of retentate within the retentate
container 16. Such sensors may be configured to measure the volume
of the retentate within the retentate container 16 without
requiring direct physical contact between any part of the sensor
and the retentate within the container 16. By way of example and
not limitation, the concentrator system 10 may include a load cell
46 for measuring the weight of the volume of retentate within the
retentate container 16, as shown in FIG. 2. The weight of the
volume of retentate may be used to calculate the volume of the
retentate using a known approximate value of the density of the
retentate. In additional embodiments, an optical sensor, a
proximity sensor, or any other type of sensor may be used to
measure the volume of the retentate within the retentate container
16.
FIG. 3 is a Nock diagram schematically illustrating an embodiment
of a control system 50 that may be used to control operation of the
sample concentrator system 10 shown in FIG. 2. The control system
50 may comprise a controller 52. The controller 52 may comprise,
for example, a microcontroller, ASIC (Application Specific
Integrated Controller), computer (e.g., a portable computer, a
desktop computer, a personal data assistant (PDA), etc.) or a
programmable logic controller. The controller 52 may comprise at
least one electronic signal processor 54 (i.e., a microprocessor)
and at least one memory device 56 (i.e., a random access memory
(RAM) device, a read only memory (ROM) device, a Flash memory
device, etc.) for storing data therein in electrical communication
with the electronic signal processor 54.
As shown in FIG. 3, the controller 52 may be configured to receive
a signal from each of the pressure gauge 42, the flow sensor 44,
and the load cell 46 previously described in relation to FIG. 2, as
well as any additional gauges, sensors, or meters of the
concentrator system 10. The controller 52 also may be configured to
control operation of the pump 12. For example, the controller 52
may be configured to relay one or more signals to the pump 12 to
cause the pump 12 to start the pump, to stop the pump, to adjust
the speed of operation of the pump, and to change the direction in
which the pup head rotates. The controller 52 also may be
configured to selectively actuate or otherwise control one or more
of the valves 34A-34E, as previously discussed with reference to
FIG. 2.
With continued reference to FIG. 3, the control system 50 may
further comprise at least one input device 58 for enabling an
operator to input one or more commands to the control system 50 of
the fluid concentrator system 10, and at least one output device 60
for outputting information to the operator. By way of example and
not limitation, the input device 58 may comprise at least one of a
button, a switch, a keypad, a touchpad or touchscreen, a keyboard,
and a mouse or other pointing device, and the at least one output
device 60 may comprise at least one of a device for emitting an
visible or audible signal, a display screen or monitor, and a
printer.
In this configuration, the control system 50 may be configured
under control of a computer program to substantially automatically
control the various elements, components, and subsystems of the
sample concentrator system 10 when concentrating a fluid sample. By
way of example and not limitation, the control system 50 may be
configured under control of a computer program (which optionally
may be recorded in memory of the at least one memory device 56 of
the controller 52) to perform the sequence of operations
illustrated in the flow chart shown in FIGS. 4A-4C.
Referring to FIG. 4A, upon receipt of an input signal received from
an operator through the input device 58, the control system may be
configured to request that the operator input the total volume of
effluent to be discharged from the effluent outlet line 20 (FIG. 2)
during a concentration process as shown at activity 60, which, in
effect, may determine the concentration factor to be achieved
during the concentration process. After the volume has been input
to the control system 50 by the operator, the control system 50 may
cycle power to the various components of the concentrator system 10
that require power and tare the load cell 46 or any other sensor,
gauge, or meter that requires taring, as shown at activity 62. The
control system 50 may be configured to ask the operator if it is
desired to enter a test mode (e.g., for calibration), as shown at
decision point 64. If yes, the control system 50 may enter the test
mode as shown at activity 66, the details of which may be
customized to particular applications and are not described in
detail herein. If the decision at decision point 64 is no, the
control system 50 may be configured to check hardware (e.g., one or
more of the pump 12, the pressure gauge 42, the flow sensor 44, and
the load cell 46) for errors, as shown at decision point 68. If one
or more of the hardware components fails the hardware check, the
process may abort and an error message may be conveyed to the
operator via the output device 60 (FIG. 3). If all hardware passes
the hardware check, the control system 50 may initialize the
hardware as shown at activity 70 and may enter a ready mode at
which it waits for an input signal from the operator to initialize
a concentration process or cycle, as illustrated at decision point
72.
If the control system 50 receives an input signal from the operator
to initialize a concentration process or cycle, the control system
50 may prime the pump 12 (FIG. 2), as indicated at activity 74. For
example, priming the pump 12 may include operating the pump 12 at a
predetermined speed for a predetermined amount of time, and then
determining whether the volume of retentate within the retentate
container 16 (FIG. 2) is greater than a predetermined minimum value
(e.g., four hundred and fifty milliliters (450 ml)), as shown at
decision point 76. If the retentate volume is below the minimum
value, the control system 50 may be configured to repeat the pump
priming activities, as shown in FIG. 4A. If the retentate volume is
above the minimum value, the control system 50 may be configured to
cause the pump 12 to operate at a predetermined speed for a
predetermined amount of time (e.g., three minutes) to cause fluid
to flow through the fluid circulation path (i.e., from the pump 12,
through the filter 14, the retentate container 16, and back to the
pump 12), as shown at activity 78 in FIG. 4A.
Referring to FIG. 4B, after the pump 12 has pumped fluid through
the fluid circulation path, the control system 50 may be configured
to reduce the volume of retentate in the retentate container 16 to
a reduced level (e.g., about two hundred and fifty milliliters (250
ml), as shown at activity 80, by closing the valve 34E (FIG. 12)
and operating the pump 12 until the reduced volume level is
achieved. After the reduced volume level of retentate has been
achieved, the control system 50 may be configured to stop the pump
12 and to provide fluid communication to the sample source, as
shown at activity 82, by opening the valve 34E. The control system
50 may be configured to then close the valve 34B and operate the
pump 12 to draw potentially contaminated fluid into the fluid
circulation path of the concentrator system 10 until an increased
desired target volume of retentate has been obtained in the
retentate container 16 (e.g., about seven hundred and fifty
milliliters (750 ml)), as shown at activity 84. After the desired
target volume of retentate has been obtained in the retentate
container 16, the control system 50 may be configured to increase
the operating speed of the pump 12 to a desired operating speed
(which may be a maximum operating speed of the pump 12), as shown
at activity 86, and to then enter a main process loop.
The control system 50 then may be configured to enter a main
process loop in which the pump 12 is operated to pump fluid through
the fluid circulation path and to selectively draw additional
potentially contaminated fluid into the fluid circulation path
through the sample inlet line 32 as required to maintain the volume
of retentate within the retentate container 16 within selected
predetermined limits as fluid exits the fluid circulation path
through the effluent outlet line 20. This overall process may
concentrate one or more harmful substances within the
retentate.
For example, as shown in FIG. 4B, the control system 50 may be
configured to determine whether the retentate volume in the
retentate container 16 is below a lower threshold level (e.g., two
hundred milliliters (200 ml)) using the load cell 46, as shown at
decision point 88. If the volume is below the threshold level, the
volume may be increased to a level within the selected
predetermined limits (e.g., five hundred milliliters (500 ml)), as
shown at activity 89. If the volume is above the lower threshold
level, the control system 50 may be configured to determine whether
the retentate volume in the retentate container 16 is below an
upper threshold level (e.g., eight hundred and fifty milliliters
(850 ml)) using the load cell 46, as shown at decision point 90. If
the volume is above the upper threshold level, the volume may be
decreased to a level within the selected predetermined limits
(e.g., seven hundred milliliters (700 ml)), as shown at activity
91.
With combined reference to FIG. 4B and FIG. 2, in the processes
described above, the volume of retentate in the retentate container
16 may be increased by, for example, closing valve 34B, opening the
valve 34E, and operating the pump 12 to draw additional sample
fluid into the circulating fluid path. The volume of retentate in
the retentate container 16 may be decreased by, for example,
opening the valve 34B, closing the valve 34E, and operating the
pump 12 to force additional effluent out from the circulating fluid
path through the effluent outlet line 20. The valve 34A also may be
dosed as necessary or desired when decreasing the volume of the
retentate within the retentate container 16.
As the pump 12 circulates fluid through the filter 14, a pressure
differential may be generated across the filter 14. In other words,
the fluid pressure in the conduit 18 may be relatively higher than
the fluid pressure in the conduit 22. The volume of effluent
discharged through the effluent outlet line 20 may be at least
partially a function of this pressure differential, and the
pressure differential may be at least partially a function of the
operating speed of the pump 12. If the valve 34C on the vent line
26 (FIG. 2) is maintained in the closed position, a back pressure
may be generated within the conduit 22 upon operation of the pump
12. Providing a back pressure within the conduit 22 (and within the
retentate container 16) of about thirteen thousand eight hundred
Pascals (13,800 Pa) (about two pounds per square inch (2 PSI)) or
more may help to stabilize the fluid level of the retentate in the
retentate container 16 and may help to force effluent out the
effluent outlet line 20 through the filter 14. This back pressure
may be a function of the pressure within the conduit 18, the flow
characteristics of the filter 14, and the state of the various
valves 34A-34E. As a result, it can be determined (e.g., using
empirical studies) what the pressure in the conduit 22 will be for
a given pressure within the conduit 18 and state of the valves
34A-34E. In other words, the pressure differential between the
conduit 18 and the conduit 22 can be deduced using the known
pressure within either the conduit 18 or the conduit 22, and the
state of the valves 34A-34E for any particular embodiment of a
concentrator system 10.
In some embodiments, it may be desirable to maintain the pressure
differential between the conduit 18 and the conduit 22 within a
predetermined range of pressures. For example valve 34A may be an
adjustable valve used to create a pressure differential. By way of
example and not limitation, it may be desirable to maintain this
pressure differential between about thirty five thousand Pascals
(35,000 Pa) (about five pounds per square inch (5 PSI)) and about
one hundred and seventy two thousand Pascals (172,000 Pa) (about
twenty five pounds per square inch (25 PSI)). Therefore, in some
embodiments, the control system 50 may be configured to monitor the
pressure within the conduit 18 using the pressure gauge 42, and to
automatically adjust the operating speed of the pump 12 so as to
maintain this pressure differential within the predetermined range
of pressures.
With continued reference to FIG. 4B, in some embodiments, the
control system 50 may be configured to allow an operator to pause
operation of the concentrator system 10 (e.g., the pump 12) at any
time during the main process loop by, for example, providing an
input signal using the input device 58 (FIG. 3). Therefore, in some
embodiments, if the volume of retentate within the retentate
container 16 is below the upper threshold level, the control system
50 may be configured to determine whether an input signal has been
received indicating that the operator wishes to pause operation of
the concentrator system 10, as shown at decision point 92. If such
a signal has been received, the control system 50 may be configured
to pause or wait until the operator provides an additional input
signal indicating that it is desired to resume operation, as shown
at activity 93. If no such signal has been received, the control
system 50 may be configured to determine whether the total volume
of effluent that has been discharged from the effluent outlet line
20 is greater than or equal to that entered by the operator during
activity 60 (FIG. 4A) as the desired target volume, as shown at
decision point 94. If the desired final volume has not been
achieved, the control system 50 may be configured to repeat the
main process loop, as shown in FIG. 4B. If the desired target
volume has been achieved, the control system 50 may be configured
to close the valve 34E to prevent additional sample fluid from
being drawn into the concentrator system 10, and to optionally
reduce the volume of retentate within the retentate container 16 to
a desired target sample volume (e.g., about one hundred milliliters
(100 ml)), as shown at activity 95.
Referring to FIG. 4C, the control system 50 may be configured to
then pause operation of the concentrator system 10 (e.g., the pump
12) to allow the operator to remove the final sample volume from
the concentrator system 10 for testing and analysis, as shown at
activity 96. In some methods, the entire retentate container 16 may
be removed from the concentrator system for transportation or
shipment to a remote location for testing and analysis. The pause
operation is preferably used to allow the operator to change the
supply side source such as a carboy. For example, a 50 liter carboy
weighs approximately 50 kg, using multiple supply side containers
may be advantageous when the source is not a large body such as a
kitchen or bath sink, lake, pond, or stream.
Optionally, after the final sample volume from the concentrator
system 10, the control system 50 may be configured to enable an
operator to perform one or more rinsing or washing operations. For
example, it may be desired to flush the system 10 with an eluent.
As shown at activity 96, fluid communication may be established
between the sample inlet line 32 and an eluent. The control system
50 may be configured to then operate the pump 12 at a predetermined
speed for a predetermined amount of time to draw the eluent into
the concentrator system 10 through the sample inlet line 32, as
shown at activity 98.
As shown at activity 100, the volume of eluent being discharged
from the concentrator system 10 through the effluent outlet line 20
may be reduced by closing the valve 34D, after which the control
system 50 may be configured to operate the pump 12 at a
predetermined speed for a predetermined amount of time to
recirculate the eluent through the fluid circulation path, as shown
at activity 102.
The control system 50 may be configured to then pause operation of
the concentrator system 10 to enable an operator to configure the
system 10 for an optional backwash process by establishing fluid
communication between the effluent outlet line 20 and a backwash
eluent, as shown at activity 104. The control system 50 may be
configured to perform a backwash sequence, as shown at activity
106. By way of example and not limitation, the backwash sequence
may comprise, for example, closing the valves 34A and 34E and
operating the pump 12 at a predetermined speed 12 for a
predetermined amount of time to draw the backwash eluent into the
concentrator system 10 through the effluent outlet line 20 and the
filter 14. Backwashing the filter 14 in this manner may help to
dislodge and otherwise free matter that has accumulated in the
hollow fibers of the filter 14, and to allow such matter to be
discharged from the concentrator system 10 through the sample inlet
line 32 or through the retentate container 16.
Optionally, embodiments of concentrator systems 10 of the present
invention may be configured as a portable system that can be
transported or shipped to a location of a potentially contaminated
fluid sample source, such as, for example, a lake, reservoir,
river, stream, or well.
FIG. 5 is a partially cut-away side perspective view of one
particular portable embodiment of the concentrator system 10 that
is represented schematically in FIG. 2. As shown in FIG. 5, the
portable concentrator system 10 includes a portable outer housing
110, which may comprise one or more handles and one or more wheels
to facilitate transportation of the concentrator system 10. As
shown in FIG. 2, the pump 12, the filter 14, and the retatentate
container 16 each may be secured within the housing 110. For
example, one or more of the pump 12, the filter 14, and the
retatentate container 16 may be structurally fastened or otherwise
secured to an internal frame member 112 positioned within the
container, and the internal frame member 112 optionally may be
fastened or otherwise secured to the interior of the housing 110.
Each of the other various elements and components of the
concentrator system 10 shown in FIG. 2 also may be secured within
the housing 110.
The portable concentrator system 10 shown in FIG. 5 may include a
power distributor 114, which may be used to distribute power to the
various components of the concentrator system 10 requiring
independent power for operation (e.g., the pump 12). The portable
concentrator system 10 may operate on power supplied by at least
one of an external power supply grid and an internal power source
(e.g., a battery, fuel cell, generator, etc.) For example, the
portable concentrator system 10 may comprise an internal battery
116 that may be used to power the various components of the
concentrator system 10.
As shown in FIG. 5, the portable concentrator system 10 also may
include various electronic components 118, which optionally may be
mounted to the internal frame member 112. The electronic components
118 may comprise, for example, the controller 52 of the control
system 50 (FIG. 3), an electronic meter for the load cell 46 (FIG.
2), electronic components associated with flow meters or pressure
gauges, relay boxes, fuse boxes, etc.
In some embodiments, the portable concentrator system 10 may
comprise one or more data ports 124 for transmitting electrical
signals between the electronic components within the housing 110
and electronic devices outside the housing 110. By way of example
and not limitation, the controller 52 of the control system 50
shown in FIG. 3 may comprise a portable computer device located
outside the housing 110, and electrical communication may be
established between the portable computer device and the other
components of the control system 50 shown in FIG. 3 (which may be
disposed within the housing 110) through one or more data ports
124. Such data ports 124 may be mounted through the wall of the
container, as shown in FIG. 5, to enable electrical communication
between the electronic components within the housing 110 and
electronic devices outside the housing 110 without requiring that a
lid or cover of the housing 110 be removed or opened.
Preferably, the housing 110 comprises one or more, more preferably
a plurality of, provisions for preventing the release of the
retentate in the retentate container 16, particularly aerosolized
retentate. In one embodiment, the housing 110 comprises one or more
windows (not shown for simplicity) to enable an operator to
visually inspect the various components of the concentrator system
10 within the housing 110 without requiring that a lid or cover of
the housing 110 be removed or opened. Preferably additional
interior enclosures within the device are also used to limit the
area of exposure upon the release of the retentate. Preferably, the
housing 110 further comprises one or more leak detection sensors,
thereby allowing for the detection, and preferably notification to
the operator, of a breach in the system. Preferably, all
electronics are contained in separate, isolated electronics
compartment 113. Preferably, the isolated electronics compartment
113 is sealed to prevent any liquids from entering the compartment,
while also reducing thermal conductivity that would otherwise heat
the retentate. This is preferred as many pathogens are sensitive to
changes in temperature, and the heat generated by the electrical
components may have an adverse impact on the results of the
viability assays. Preferably, the electronics compartment 113 is
designed to be removed for decontamination without rexposing the
sensitive electronics to potentially harsh chemical disinfectants.
Thus, even if the enclosed fluid path were breached, resulting in
contamination of that portion of the device, a substantial portion
of the device could be readily decontaminated and rapidly restored
to operations. The entire device is preferably enclosed in an outer
enclosure. The outer enclosure is preferably designed to prevent
penetration of environmental elements (dust and rain) from the
outside, as well as containing any potential spills, leaks or
aerosols within the device.
Preferably, the filter 14, pressure transducer 42 as shown in FIG.
2, and the various conduit are all designed for user removal to
prevent cross contamination. Preferably, they are designed for user
removal by the use of one or more quick disconnect fittings that
act as shut-off valves when disconnected. Preferred embodiments, as
described above, have been able to detect with 99% confidence 6
bacterial endospores in 100 liters of water. Therefore, with this
level of sensitivity, it is essential the various components be
replaced before each run to ensure that cross contamination is
prevented.
FIG. 6 is a schematic top plan view of the portable concentrator
system 10 shown in FIG. 5 and illustrates the physical layout of
the various operational elements, components, and subsystems of the
portable concentrator system 10 within the housing 110. Many other
physical layouts are contemplated and embodiments of concentrator
systems of the present invention may have physical layouts other
than that shown in FIGS. 5 and 6.
As shown in FIGS. 5 and 6, a coupler 126 also may be mounted
through the housing 110 for coupling an external conduit (not
shown) to the sample inlet line 32 (FIG. 2), and an additional
coupler 126 also may be mounted through the housing 110 for
coupling another external conduit (not shown) to the effluent
outlet line 20 (FIG. 2). By way of example and not limitation, the
couplers 126 may comprise, for example, straight connectors, hose
connectors, barb connectors, ISO connectors, sanitary connectors,
quick disconnect connectors, or Luer Lock type connectors. In this
manner, the entire concentrator system 10 may be operated without
requiring that the housing 110 be opened during a concentration
process until it is necessary or desired to remove the final
concentrated volume of retentate within the retentate container 16
for testing and analysis.
In typical applications of the invention the harmful substances are
preferably detected using culturable methods, molecular methods or
immunoassay based methods. For culturable methods the harmful
substance (i.e., microorganisms) in the retentate are preferably
grown on growth media such as agar plates and allowed to incubate
until colony forming units are visible. The resulting colony
forming units are then preferably detected and counted, and the
quantity of units is directly related to the amount of the harmful
substance in the original sample. In these methods, retentate
containing the harmful substance is preferably added directly to
the growth media or a further concentration can occur through
centrifugation or membrane filtration in which the centrifuged
pellet or the membrane filter, respectively, is placed onto the
growth media. If the harmful substance is a virus, a portion of the
retentate containing the harmful substance is preferably placed
onto a layer of viable cells growing on an agar plate. The harmful
substance preferably has a cytopathic effect on the cells such that
cell death occurs in the proximity of the virus. Cell death is
visible on the layer of cells and the amount of the harmful
substance is preferably correlated to the number of cell death
areas on the plate.
For molecular methods, such as polymerase chain reaction, the
harmful substance's DNA or RNA is preferably analyzed. The amount
of molecular material is preferably used to estimate the amount of
the harmful substance in the original sample of retentate.
For immunoassay based methods antibodies and/or antigens of the
harmful substance are preferably added to portion of the retentate
containing the harmful substance. The antibody/antigen reacts with
the harmful substance, and the resulting product detected and
quantified. The amount of the product is preferably directly
related to the amount of the harmful substance in original
sample.
Embodiments of sample concentrator systems of the present invention
may provide various benefits and improvements over previously known
concentrator systems. For example, embodiments of sample
concentrator systems of the present invention may be automated,
portable, easily configurable in the field, and may minimize or
reduce the risk of exposure of an operator to potentially harmful
pathogens or other harmful substances being concentrated by the
concentrator systems.
Preferred embodiments, as described above, have been able to detect
with 99% confidence 6 bacterial endospores in 100 liters of water.
This sensitivity is required to be able to detect low-level harmful
substances that would otherwise be undetectable. In preferred
embodiments, the system is capable of detecting less than 100, even
as low as 5 pathogens in 100 L of water container.
While the invention may be susceptible to various modifications and
alternative forms, specific embodiments have been shown by way of
example in the drawings and have been described in detail herein.
However, it should be understood that the invention is not intended
to be limited to the particular forms disclosed. Rather, the
invention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the following appended claims.
* * * * *